We investigate the characteristics of airbrush spray coated polymer solar cells based on a mixture of poly(3-hexyl thiophene) and (6,6)-phenyl C-61-butyric acid methyl ester, deposited with different settings. We show smooth films yielding spray coated solar cells with power conversion efficiencies of 2.8%. In addition, we find that the spray coating technique allows the realization of polymer solar cells with a structural gradient in the vertical direction: the femtoliter scale droplets, distinctive of spray coating, dry very rapidly and subsequent layers can be deposited from the same solvent, without completely dissolving the underlying layers. (C) 2008 Elsevier B.V. All rights reserved.